BIOENGINEERING

ORTHOSIS

Characteristics of IDEAL ORTHOSIS

• FUNCTION• COMFORT• COSMESIS• FABRICATION• COST

FUNCTION

• Meets the individuals mobility needs ad goals• Maximizes stance phase stability• Minimizes abnormal alignment• Minimally compromises swing clearance• Effectively pre-positions the limb for initial

contact• Is energy efficient with the individual’s

preferred assistive device

COMFORT

• Can be worn for long periods without damaging skin or causing pain

• Can be easily donned and doffed (eg, considering clothing, footweare, toileting)

COSMESIS & COST

• Meets the individual’s need to fit in with peers• Can be made with minimal initial cost,

minimal cost for maintainence.

FABRICATION

• Can be made in the shortest period of time• Uses a minimally complex design• Has some degree of adjustability to enhance

initial fitting• For children, responds to growth or change

over time• Is durable: stands up to stress/strain of daily

activity

PRINCIPLES UNDERLYING ORTHOTIC DESIGN

• PRESSURE= FORCE/AREA The forces are distributed over large surface

areas to minimize pressure on skin and soft tissue.

• TORQUE = FORCE * DISTANCEThe forces applied in such a way that a large

moment arm reduces the amount of force needed to control the joint

PRINCIPLES

• Control direction of primary force direction of counter –forces

• EQUILIBRIUM (SUM OF ALL FORCES)= 0The sum of primary force and opposing counter-

forces of each control system equals zero.

TOE-SPREADER

TOE-SPREADER WITH HALLUX CORRECTION

MEDIAL HEEL WEDGE

ANKLE-FOOT ORTHOSES

• Used to control the lower extremity during each phase of the gait cycle for individuals with neuromuscular or musculoskeletal impairments.

• Categories 1. Static2. Dynamic

AFO

COMPONENTS • Foundation- Consists of shoe and plastic/

metal component• Ankle control• Foot control• Superstructure

PARTS OF ANKLE- FOOT ORTHOSIS

TYPES OF AFO

• Static AFO• Dynamic AFO• Supramalleolar Orthosis• Tone reducing Orthosis• Floor reaction Orthosis• Posterior leaf spring Orthosis

STATIC ANKLE FOOT ORTHOSIS

SAFOACTIONS• Control ankle position

throughout stance• Provide stance phase Stability

via ankle-knee coupling• Assist limb clearance in swing• Pre-position foot for IC by

heel• Distal trim line behind

metatarsal heads or extended toe-plate

INDICATIONSSignificant hypertonicity with seriously impaired motor control at ankle and knee.

CONTRA-INDICATIONSLMN paralysis ( flaccidity)Hypotonicity as primary problem

Dynamic AFO

DAFOACTIONS• Stabilize sub-talar and

tarsal joints in stanceINDICATIONS•FLEXIBLE PES PLANUS•MILD TO MODERATE SPASTIC DIPLEGIC•HEMIPLEGIC CP•HYPOTONIC CP

CONTRAINDICATIONS•RIGID FOOT DEFROMITY

KAFOKNEE-ANKLE-FOOT ORTHOSIS

PARTS • Shoe• Foundation• Ankle control• Knee control• Superstructure

KAFOKnee, ankle, foot orthosis, custom may include knee joints. Joints may be locking or adjustable in flexion and extension.Indications:Polio, MS, paresis, knee instability/buckling.Contraindications:Morbid obesity, dependent patient with poor cognition and upper extremity weakness combined with poor support system.

Knee Control

• Hinge joint

• Offset joint

• Provide medial-lateral and hyperextension restriction while permitting knee flexion

• Hinge placed posterior to midline of leg. Weight falls anterior to offset joints, stabilizing knee in extension during early stance phase.

• Drop ring lock

• Pawl lock with bail release

• When client sands with full knee extension, the ring drops, preventing knee from bending.

• Provides simultaneous locking of both uprights. The pawl is a spring-loaded projection that fits into a notched disk. The patient unlocks the brace by pulling upward on the posterior bail.

'Bail Lock' Knee joint. This joint remains locked until the spring-loaded release bar that connect the two mechanical knee joints is lifted. It automatically locks when the user fully extends their limb, i.e., when rising from a chair.

Polycentric Knee joint to allow knee flexion with less bunching of the skin behind the knee and to reduce vertical movement of the device when the knee bends.

Offset free motion knee joint with ‘Drop locks’ to maintain knee extension

BIOMECHANICAL PRINCIPLES APPLIE TO THE DESIGN AND FITTING OF KAFO

• Mediolateral stability and toe off must be provided during swing phase

• Knee stability needs to be provided during the stance and simulated push-off

• Excessive force should not be applied to the knee.

• Orthosis must be fitted with knee in extension in order to reduce the bending moment at the knee.

Contd…

• Rigid ankle joint provides more stability• Posterior thigh strap is necessary to restrain orthosis

from sliding off the leg while sitting• Dorsiflexion stop with sole plate extended to the

metatarsal head area facilitates push off and reduce energy consumption.

• Major portion of total knee stabilizing force should be applied below the knee in order to reduce the shear forces on the knee ligaments

Contd…

• Straps should distribute force over large and tolerant area i.e. patella tendon and supra patellar area

• Stabilizing straps should be applied as close to the knee joint as possible to reduce the force require to counterbalance a bending moment

Craig-Scot KAFO

PARTS• Shoe reinforced with

transverse an longitudinal plates

• BiCAAL ankle joints set in 10 degree dorsiflexion

• Pretibial band• Pawl lock with bail release• Single thigh band

CRAIG SCOTT KAFO

INDICATIONS• Paraplegics • Thoracic spinal cord

injuryGAIT PATTERN• Swing-to or swing-

through with aid of crutches or a walker

ADVANTAGES• Medio-lateral foot stability

provided by metatarsal bar• Enable a patient to stand

with sufficient backward lean so as to prevent untoward hip or trunk flexion.

• Functional • Easy to don and doff• Light weight as compared to

standard KAFO

HKAFO

HKAFO

Indications• Weak hip musculature• Hip instabilityParts• Pelvic band• Hip joint

RGO

• Bilateral HKAFOPRINCIPLE- ipsilateral hip flexion leads

to contra lateral hip extension and vice versa. It consists of hip joints that transfer forces from one hip to other by Bowden cables

INDICATIONS • Active hip flexion but no hip

extension• Paraplegic L1 levelDISADVANTAGES• High energy cost requirement• Slow speed

THKAFOPARAPODIUM

CERVICAL ORTHOSISImmobilizing cervical spine is difficult because• Most mobile part in spine• Has small body surface• Limited pressure tolerant areas like chin, occiput• Different types of predominant movement at different levelsFunctions• Positions the head• Limits movement in flexion, extension, rotation and lateral

rotation• Unload the cervical spine by bearing part of weight of the skull

CERVICAL ORTHOSIS

Classification• Cervical collars• Poster appliances• Cervicothoracic orthosis• Halo devices

Commonly used• Soft and semi-rigid

cervical collars• Philadelphia orthosis• SOMI brace• Poster orthosis• Minerva body jacket• Halo jacket or vest

SOFT CERVICAL COLLAR• Made of foam and rubber

covered by stockinetADVANTAGES• low cost• easy to fabricate• tolerated by patient• provides warmth and

psychological comfortDISADVANTAGES• Does not restrict cervical

motion in any plane.

PHILADELPHIA COLLARPARTS• Anterior and psoterior struts, with

molded mandilbular and occipital support. Extends to uper thoracic region anteriorly and posteriorly

ADVANTAGES• Restricts flx/ext due to chin and

occiput support and thoracic extension

DISADVANTAGES• Ineffective in controlling rotation

and lateral bending• Pressure over clavicle

SOMI BRACE(Sternal Occipito Mandibular Immobilization)

PARTS• Sternal plate• One anterio stripr to hold chin• Two rigid metal rods from

anterior to posterior to occiput support.

ADVANTAGES• No posterior post, can be used it

supine• Light weight for donning and

doffing• Controls flexion effectively at C1–

C3

SOMI BRACE

Indications:• Atlantoaxial instability caused by rheumatoid arthritis

• Neural arch fractures of C2, because flexion causes instability

Contraindications:The SOMI controls extension less effectively than do other orthoses.Flexion and extension control at C3-T1: better served with a Minerva

HALO DEVICE• Rigid metal/graphite ring

attached to skull by four fixation pins

• 4 posters which are attached to ring proximally- 2 anteriorly, 2 posteriorly and distally to polypropylene vest.

Polyethylene vest• Half vest- level of nipples• Short- level of 12h rib• Full vest- level of iliac crest

Halo orthosisINDICATIONS: • Dens type I, II, or III fractures of C2 • C1 fractures with rupture of the transverse ligament• Atlantoaxial instability from rheumatoid arthritis, with ligamentous

disruption and erosion of the dens• C2 neural arch fractures and disc disruption between C2 and C3. • Bony, single-column cervical fractures• Cervical arthrodesis – Postoperative• Cervical tumor resection in an unstable spine – Postoperative• Debridement and drainage of infection in an unstable spine – Postoperative• Spinal cord injury (SCI)• The halo is the best orthosis for use in controlling rotation and lateral

bending at C1-C3.

Halo orthosis• Complications:

• Neck pain or stiffness – 80%• Pin loosening – 60%• Pin site infection – 22%• Scarring – 30%• Pain at pin sites – 18%• Pressure sores – 11%• Redislocation – 10%• Restricted ventilation – 8%• Dysphagia – 2%• Nerve injury – 2%• Dural puncture – 1%• Neurological deterioration – 1%• Avascular necrosis of the dens• Ring migration• Inadequate bony healing• Inadequate ligamentous healing

Contraindications:1. Concomitant skull fracture

with cervical injury2. Damaged or infected skin

over pin insertion sites3. Cervical instability with 2-

or 3-column injury4. Cervical instability with

rotational injury involving facet joints

Minerva Body Jacket• Motion restriction at C5-C7• Anterior and posterior chest

plates connected by shoulder straps

• Chin plate • Occipital piece that connect

to anterior and posterior struts.

• The brace has poor control of flexion, extension, rotation, and lateral bending at C1-C2.

MINERVA JACKETIndications• Minimally unstable

fractures from C3-T2• Internal fixation from C3-T2Motion restrictions:

• Limitation of flexion and extension from C3-T2.

Contraindications:• Flexion control at C1-C5: Better served with a SOMI

TLSO (thoraco-lumbar-sacral)

• For fractures between T6 and L3. • Provide support and immobilization of the

thoracic and lumbar regions following various surgical procedures/ traumatic injuries

• Help in treatment of post-operative thoracic/lumbar fusion, laminectomy or discectomy, compression fractures, degenerative disc disease, osteoporosis, single column spinal instability immobilization, and facet syndrome.

JEWETT BRACE• The Jewett orthosis uses a

3-point pressure system to control flexion

• PARTS-1 posterior and 2 anterior pads.

• The anterior pads place pressure over the sternum and pubic symphysis.

• The posterior pad places opposing pressure in the midthoracic region.

JEWETT BRACEMotion restrictions• Limits flexion and extension between T6-L1Indications:• Symptomatic relief of compression fractures T6-L1• Immobilization after surgical stabilization of thoracolumbar fractures

Contraindications:• Three-column spinal fractures involving anterior, middle, and posterior spinal structures• Compression fractures above T6, because segmental motion increases above the sternal pad• Ineffective in limiting lateral bending and rotation of the upper lumbar spine

ANTERIOR SPINAL HYPEREXTENSION (ASH) BRACE

Anterior Spinal Hyperextension (ASH) brace features • Anterior sternal • Pubic pads • Posterior pad and • Strap around the thoracolumbar

region.• Sternal and pelvic pads attach to the

anterior, metal, cross-shaped bar.• The brace is easy to don and doff,

but it is difficult to adjust.• It provides greater breast and

axillary pressure relief than does the Jewett hyperextension TLSO.

ASH BRACE

Motion Restrictions:• Limits flexion and extension at T6-L1Indications:• Flexion immobilization to treat thoracic and lumbar vertebral body fractures T6-L1• Reduction of kyphosis in patients with osteoporosis

Contraindications:• Three-column spinal fractures involving anterior, middle, and posterior spinal structures• Compression fractures caused by osteoporosis• Ineffective in limiting lateral bending and rotation of the upper lumbar spine

CTLSO-MILWAUKEE BRACE

• CTLSO • Helps maintain postoperative correction in

patients with scoliosis secondary to polio. • Stimulates corrective forces in the patient. • Proper fit allows consant usage of trunk

muscles, disuse atrophy does not occur. • The brace has an open design.

FEATURES• Plastic pelvic mold• 2 posterior upright• 1 anterior upright• Thoracic pad• Transverse pad attached

to uprights• Neck ring

Features

• Constant force provided by the plastic pelvic mold. • The pelvic portion - reduces lordosis, derotates the spine, and

corrects frontal deformity.• The uprights have localized pads that apply transverse force,

which is effective for small curves. • The thoracic pad, main corrective force, creates a righting

response to an upright posture.• The uprights are perpendicular to the pelvic section, so any

leg-length discrepancy should be corrected to level the pelvis. • The neck ring - gives longitudinal traction. .

Milwaukee braceIndications:

• Used for curves in which the apex is above T7.• Patients with a Risser score of I-II, as well as a curve that is greater than 20-30° and that progresses by 5° over 1 year• Curves of 30-40°, but not curves of less than 20°.• Curves of 20-30°, with no year-over-year progression, require observation every 4-6 months.

Duration of use:• Daily use ranges from 16-23 hours per day.• Treatment should continue until the patient is at Risser stage IV or V.• If the curve is greater than 30°, consider continued use of the brace for 1-2 years after maturity, because a curve of this magnitude is at risk of progression.

Milwaukee brace

PROBLEMS WITH BRACE• Jaw deformity• Skin breakdown• Unsightly appearance• Difficulty with mobility• Difficulty with transfers• Increased energy

expenditure with ambulation

CAUSES OF FAILURE• Poor patient

compliance• Improper fit• Curves below T7

TLSO- BOSTON BRACE• TLSO with built-in lumbar flexion• can be worn under clothes. • Lumbar flexion- achieved

through posterior flattening of the brace and extension of the mold distally to the buttock.

• Braces with superstructures have a curve apex above T7.

• Curves with an apex at or below T7 do not require superstructures to immobilize cervical spine movement.

• Height cannot be ajuste.

BOSTON BRACE

Indications:• A curve of 20-25° with

10° progression over 1 year

• A curve of 25-30° with 5° progression over 1 year

• Skeletally immature patients with a curve of 30° or greater

Complications• Local discomfort• Hip flexion contracture• Trunk weakness• Increased abdominal

pressure• Skin breakdownCauses of failure• Curve above T7• Improper fit• Poor patient compliance